Dataset Information

DNA double-strand breaks in heterochromatin elicit fast repair protein recruitment, histone H2AX phosphorylation and relocation to euchromatin.

ABSTRACT: DNA double-strand breaks (DSBs) can induce chromosomal aberrations and carcinogenesis and their correct repair is crucial for genetic stability. The cellular response to DSBs depends on damage signaling including the phosphorylation of the histone H2AX (?H2AX). However, a lack of ?H2AX formation in heterochromatin (HC) is generally observed after DNA damage induction. Here, we examine ?H2AX and repair protein foci along linear ion tracks traversing heterochromatic regions in human or murine cells and find the DSBs and damage signal streaks bending around highly compacted DNA. Given the linear particle path, such bending indicates a relocation of damage from the initial induction site to the periphery of HC. Real-time imaging of the repair protein GFP-XRCC1 confirms fast recruitment to heterochromatic lesions inside murine chromocenters. Using single-ion microirradiation to induce localized DSBs directly within chromocenters, we demonstrate that H2AX is early phosphorylated within HC, but the damage site is subsequently expelled from the center to the periphery of chromocenters within ? 20 min. While this process can occur in the absence of ATM kinase, the repair of DSBs bordering HC requires the protein. Finally, we describe a local decondensation of HC at the sites of ion hits, potentially allowing for DSB movement via physical forces.

SUBMITTER: Jakob B

PROVIDER: S-EPMC3159438 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

DNA double-strand breaks in heterochromatin elicit fast repair protein recruitment, histone H2AX phosphorylation and relocation to euchromatin.

Jakob Burkhard B Splinter Jörn J Conrad Sandro S Voss Kay-Obbe KO Zink Daniele D Durante Marco M Löbrich Markus M Taucher-Scholz Gisela G

Nucleic acids research 20110421 15

DNA double-strand breaks (DSBs) can induce chromosomal aberrations and carcinogenesis and their correct repair is crucial for genetic stability. The cellular response to DSBs depends on damage signaling including the phosphorylation of the histone H2AX (γH2AX). However, a lack of γH2AX formation in heterochromatin (HC) is generally observed after DNA damage induction. Here, we examine γH2AX and repair protein foci along linear ion tracks traversing heterochromatic regions in human or murine cell ...[more]

PMID: 21511815

Similar Datasets

Project description:This series is a supplementary data set for the manuscript titled "Postreplicative recruitment of Cohesin to double-strand breaks is required for DNA repair" All data shown in the paper plus duplicate experiments were registered (15 ChIP-chip data). Experimental design: 1. Type of experiment: ChIP (Chromatin immunoprecipitation) analysis hybridized to high density oligonucleotide arrays. The S. cerevisiae chromosome VI array described by Katou et al. (2003) Nature 424, 1078-83 and the newly developed S. cerevisiae chromosomes III-VIa have been used. 2. Experimental factors: Distribution of the sister chromatid cohesion protein Scc1, before and after induction of a DNA double strand break (dsb) on chromosome III, V and VI in G2/metaphase cells were analysed (Benomyl arrested cells). 3. Number of hybridizations performed: ChIP analysis: 15 4. Hybridisation design: ChIP analysis: comparison of ChIP fraction with SUP (supernatant) fraction 5. Quality control: Duplication of experiments, confirmation of recruitment of the analysed protein to a dsb by induction of breaks at three different positions in the genome. Mock hybridisation of samples immunoprecipitated from cells containing no tag recognized by antibody used. Checking of the ChIP fraction by Western blotting. 6. URL of supplemental website: GEO Accession number: GSE1905 Web site: http://chromosomedynamics.bio.titech.ac.jp Samples used, extract preparation and labeling: 1. Origin of the biological sample Budding yeast (Saccharomyces cerevisiae). 2. Manipulation of the samples and the protocols used: Mitotic budding yeast cells were synchronised in G2/M with Benomyl (80 ug/ml) Cells were fixed 30 minutes at room temperature plus over night in 1% formaldehyde at 4C. 3. Protocols for preparing extracts: ChIP analysis: Extract preparation was processed following the Shirahige lab protocol (http://chromosomedynamics.bio.titech.ac.jp ). 5x10^8 cells were disrupted using Multi-Beads Shocker (MB400U, YASUI KIKAI, Osaka). Whole cell extract was sonicated to obtain 400-600 bp genomic DNA fragments. Anti-Flag monoclonal antibody M2 (Sigma-Aldrich Co., St Louis, MO) coupled to Dynabeads (Dynal, protein A Dynabeads) were used for chromatin immunoprecipitation. The immunprecipates were eluted and incubated over night at 65Â¨Â¬C to reverse the cross-link. Immunoprecipitated genomic DNA was incubated with proteinase K, extracted 2 times with phenol/chloroform/isoamylalcohol, precipitated, resuspended in TE and incubated with RnaseA. The DNA was then purified using the Qiagen PCR purification kit, and concentrated by ethanol precipitation. The DNA was amplified by PCR after random priming. 10 ug of amplified DNA was digested with Dnase I to a mean size of 100 bp. After Dnase I inactivation at 95Â¨Â¬C, fragments were labelled as detailed below. 4. Labeling protocol DNA fragments were end-labeled by addition of 25 U of Terminal Transferase and 1 nmol Biotin-N6ddATP (NEN) for 1 hour at 37C as previously described by Winzeler et al. (Science. 281, 1194-1197, 1998). The entire sample was used for hybridization. 5. Hybridization procedures and parameters: Hybridization, blocking and washing were carried out as previously described (http://chromosomedynamics.bio.titech.ac.jp). Each sample was hybridized to the array in 150 ul containing 6xSSPE; 0.005% TritonX-100; 15 ug fragmented denatured salmon sperm DNA (Gibco-BRL); 1 nmole 3â??biotin labelled control oligonucleotide (oligo B2, Affymetrix). Samples were denatured at 100C for 10 minutes, and then put on ice before being hybridized for 16 hours at 42C in an hybridization oven (GeneChip Hybri. Oven 320, Affymetrix). Washing and scanning protocol (FlexMidi-euk2v3-450) provided by Affymetrix was performed automatically on a fluidics station (GeneChip fluidics station 400, Affymetrix). 6. Measurement data and specifications: S. cerevisiae arrays were scanned using the HP GeneArray Scanner (Affymetrix) at an emission wavelength of 560 nm, resolution 7.5 uM. Grids were aligned to scans following the library array description. Primary data analyses were carried out using Affymetrix Microarray Suite Ver.5.0 software to obtain signal intensity, fold change value, change p-value and detection p-value. The detailed information of this analysis is available at http://www.affymetrix.com/support/technical/whitepapers/sadd_whitepaper.pdf and http://www.affymetrix.com/support/technical/technotes/statistical_reference_ guide.pdf To discriminate significant signals for binding to DNA (dark grey signals), signals from the ChIP fraction scan were compared to the SUP (supernatant) fraction scan using the 3 following criteria: first, the signal reliability was judged by the detection p-value of each locus (p-value <=0.025); secondly, reliability of binding ratio was judged by change p-value (p- value <=0.025); thirdly, only clusters of at least 3 contiguous loci responding to the 2 previous criteria were selected as significantly enriched locus. The light grey signals represent the statistically not significantly enriched signals. The software to present the result (chr6viewer) is available at http://everythingchromovi.gsc.riken.go.jp. The raw and transformed data files are available at GEO database website and at our web site http://chromosomedynamics.bio.titech.ac.jp. 6. Array Design 1. General array design: in situ synthesized arrays by Affymetrix 2. Availability of arrays: commercially available from Affymetrix 3. Location and ID of each spot on arrays: available at our web site (http://chromosomedynamics.bio.titech.ac.jp) and from Affymetrix on request 4. Probe type: oligonucleotide 5. The arrays used in this study can be purchased from Affymetrix: Chromosome VI S.cerevisiae: rikDACF, P/N# 510636 Chromosome III,IV,V,VIa S.cerevisiae: SC3456a520015F, P/N# 520015 Keywords: other

Project description:Complex DNA double-strand break (DSB), which is defined as a DSB coupled with additional strand breaks within 10 bp in this study, induced after ionizing radiation or X-rays, is recognized as fatal damage which can induce cell death with a certain probability. In general, a DSB site inside the nucleus of live cells can be experimentally detected using the γ-H2AX focus formation assay. DSB complexity is believed to be detected by analyzing the focus size using such an assay. However, the relationship between focus size and DSB complexity remains uncertain. In this study, using Monte Carlo (MC) track-structure simulation codes, i.e., an in-house WLTrack code and a Particle and Heavy Ion Transport code System (PHITS), we developed an analytical method for qualifying the DSB complexity induced by photon irradiation from the microscopic image of γ-H2AX foci. First, assuming that events (i.e., ionization and excitation) potentially induce DNA strand breaks, we scored the number of events in a water cube (5.03 × 5.03 × 5.03 nm3) along electron tracks. Second, we obtained the relationship between the number of events and the foci size experimentally measured by the γ-H2AX focus formation assay. Third, using this relationship, we evaluated the degree of DSB complexity induced after photon irradiation for various X-ray spectra using the foci size, and the experimental DSB complexity was compared to the results estimated by the well-verified DNA damage estimation model in the PHITS code. The number of events in a water cube was found to be proportional to foci size, suggesting that the number of events intrinsically related to DSB complexity at the DNA scale. The developed method was applicable to focus data measured for various X-ray spectral situations (i.e., diagnostic kV X-rays and therapeutic MV X-rays). This method would contribute to a precise understanding of the early biological impacts of photon irradiation by means of the γ-H2AX focus formation assay.

Dataset Information

DNA double-strand breaks in heterochromatin elicit fast repair protein recruitment, histone H2AX phosphorylation and relocation to euchromatin.

Publications

DNA double-strand breaks in heterochromatin elicit fast repair protein recruitment, histone H2AX phosphorylation and relocation to euchromatin.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets